System for imaging of light-sensitive media

ABSTRACT

A digitized video system having a processor and a video memory. The processor converts a stream of digital information to extract the information in a format to be usable with a moving display surface. A spatial light modulator is connected to a video memory connected to the processor to display the information on a moving display surface.

CROSS REFERENCE TO RELATED PATENTS AND APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.07/925,284, filed Aug. 4, 1992, now U.S. Pat. No. 5,446,479, issued Aug.29, 1995, which is a continuation of U.S. patent application Ser. No.07/709,087, filed May 30, 1991, now abandoned, which is a continuationof U.S. patent application Ser. No. 07/315,660, filed Feb. 27, 1989, nowabandoned.

    __________________________________________________________________________    U.S. Pat. No. 5,214,240                                                                    SLM PROJECTION SYSTEM WITH                                                                      issued 05/25/93                                                                      TI-13971A                                            RANDOM POLARITY LIGHT                                            U.S. Pat. No. 5,192,946                                                                    DIGITIZED COLOR VIDEO DISPLAY                                                                   issued 03/09/93                                                                      TI-13972B                                            SYSTEM                                                           U.S. Appln. No. 07/995,570                                                                 APPARATUS AND METHOD FOR                                                                        filed 12/22/92                                                                       TI-13973B                                            IMAGE PROJECTION                                                 U.S. Appln. No. 08/472,377                                                                 APPARATUS AND METHOD FOR                                                                        filed 6/7/95                                                                         TI-13973B.1                                          IMAGE PROJECTION                                                 U.S. Pat. No. 5,287,096                                                                    VARIABLE LUMINOSITY DISPLAY                                                                     issued 02/15/94                                                                      T13974B                                              SYSTEM                                                           U.S. Pat. No. 5,162,787                                                                    APPARATUS AND METHOD FOR                                                                        issued 11/10/92                                                                      TI-13975A                                            DIGITIZED VIDEO SYSTEM                                                        UTILIZING A MOVING DISPLAY                                                    SURFACE                                                          U.S. Pat. No. 5,214,419                                                                    PLANARIZED TRUE 3-D DISPLAY                                                                     issued 5/25/93                                                                       TI-13976A                               U.S. Pat. No. 5,170,156                                                                    MULTI-FREQUENCY 2-D DISPLAY                                                                     issued 12/08/92                                                                      TI-13977A                                            SYSTEM                                                           U.S. Pat. No. 5,079,544                                                                    STANDARD INDEPENDENT                                                                            issued 01/07/92                                                                      TI-13978                                             DIGITIZED VIDEO SYSTEM                                           U.S. Pat. No. 5,446,479                                                                    MULTI-DIMENSIONAL ARRAY                                                                         issued 08/29/95                                                                      TI-13979B                                            VIDEO PROCESSOR SYSTEM                                           U.S. Appln. No. 08/397,514                                                                 APPARATUS AND METHOD FOR                                                                        filed 3/1/95                                                                         TI-13979B.1                                          DIGITIZED VIDEO SYSTEM                                           U.S. Appln. No. 08/408,765                                                                 MULTI-DIMENSIONAL ARRAY                                                                         filed 3/22/95                                                                        TI-13979B.2                                          VIDEO PROCESSOR SYSTEM                                           U.S. Pat. No. 5,128,660                                                                    POINTER FOR 3-D DISPLAY                                                                         issued 7/7/92                                                                        TI-13980                                U.S. Pat. No. 5,206,629                                                                    SLM AND MEMORY FOR DIGITIZED                                                                    issued 04/27/93                                                                      TI-13981A                                            VIDEO DISPLAY                                                    U.S. Pat. No. 5,272,473                                                                    REDUCED-SPECKLE DISPLAY                                                                         issued 12/21/93                                                                      TI-14037A                                            SYSTEM                                                           U.S. Appln. No. 08/478/295                                                                 MIRROR MAGNIFIED VIDEO                                                                          filed 6/7/95                                                                         TI-14054A.1                                          DISPLAY                                                          U.S. Appln. No. 08/520,230                                                                 MIRROR MAGNIFIED VIDEO                                                                          filed 8/28/95                                                                        TI-14054B                                            DISPLAY                                                          __________________________________________________________________________

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus and methods for manufacturingdigitized video systems and integrated circuits and devices therefor.

2. Description of the Prior Art

The present invention is useful in the field of graphics and videodisplay systems such as displays for computer systems, terminals andtelevisions. Recently there has occurred a large demand for largerand/or higher resolution viewing surfaces than can be provided byconventional video display devices such as cathode ray tubes (CRTs) orliquid crystal displays (LCDs). This has been driven by consumer demandsfor larger televisions (TVs) and by the need for large audience viewingof either shows or computer generated screens in conferences.

LCDs, which are used for small computer systems and terminals,especially for laptop and portable computers, use individual liquidcrystal cells for each pixel on the LCD. LCDs are temperature sensitive,difficult to produce in large sizes, slow in changing state, and requireexternal light sources for viewing.

To overcome the size limitation of LCDs, there have been attempts toconstruct projection systems using an LCD as a spatial light modulator(SLM). Unfortunately, several problems still remain. The LCD isinherently slow and thus a rapidly changing image will "smear." Theresolution of the LCD is restricted by the drive complexity. Further,the drive complexity also requires that the size of the LCD willgenerally by proportionally related to the resolution. This means thatthe projection optics will have to be large and correspondinglyexpensive for a high-resolution system. Another problem is that thelight transmitted through (or reflected from) the LCD will be polarized.This may result in non-linear perception of brightness from the centerof vision to the periphery.

The most popular display system is the CRT. In a cathode ray tube, ascanning electron beam having a varying current density, is scannedacross a light emitting phosphor screen. This light emitting phosphorscreen is bombarded by the electron beam and produces light in relationto the magnitude of the current density of the electron beam. These mayalso be used in a direct view or projection mode. However, these sufferfrom various disadvantages. The first of these is cost.

The higher cost is dictated by the difficulties in constructing largedisplay tubes (at present there are 45 inch tubes being manufactured).Another reason for the cost is the huge amount of raw materials (inparticular the glass) required. This translates to a very heavy displaythat is not easily transportable.

Resolution is also a problem for CRTs. There are two major reasons forthis. The first relates to the shadow mask used in color CRTs. A shadowmask is used to separate the color phosphors used to generate the threeprimary colors (red, blue, and green), and to help guide the electronbeam used to excite the phosphors. The brightness of a pixel is relatedto the size of the phosphor spot. However, as the phosphor spot size isincreased, the shadow mask must be made larger and becomes more visible.Brightness is also related to the drive from the electron beam. As thedrive increases, so does the brightness. Unfortunately, the shadow maskis also sensitive to the electron beam and will thermally distort underhigh drive. The image is then blurred both by the shadow mask becomingmore visible and by the electron beam being deflected toward an unwantedphosphor.

The second resolution limiter is rastering. All pixels to be illuminatedare sequentially scanned by an electron beam. This beam is swept in araster back and forth across the phosphors. In general, the beam isturned off when tracing back across the phosphors (known as the retracetime) and is also turned off when returning to the starting point(vertical blanking interval). While this is not a theoretical limitation(all phosphor points can be accessed), it is a practical limitation.This is because the fluorescence of the phosphors begin decaying as soonas the electron beam moves to the next location. The electron beam mustreturn before the human eye can perceive the decay or else the displaywill flicker. Longer persistence phosphors can be used to compensate,but they suffer from a smear effect when the display data changes.

Rastering has another insidious side-effect. It places an upper limit onthe perceived brightness of a display. As discussed above, a phosphorcan only be driven for a very short period of time, and will then startto decay. If the phosphor is driven hard, then it will start to bloom(i.e. it will start to excite neighboring pixel locations) and blur thedisplay. If the phosphor was continuously excited for an extended time,it would appear to be brighter than if it was excited only for theraster period. This is because the human eye has an integration time ofapproximately 0.1 seconds for bright sources of light and approximately0.2 seconds for dimmer sources.

Projection CRT based systems do not suffer from the shadow maskproblems. However they are expensive as they usually require three CRTs(one each of red, blue, and green). Also, they suffer badly from lowbrightness (due to having expand the image generated). This isparticularly true when a single CRT is used in a projection mode. Eithertype has all of the other raster related problems. In addition, whenused in back-projection configurations, they are very large due to thecomplex optical paths required.

Another drawback to conventional display systems is that they areprimarily analog. Even if the information to be displayed is stored indigital form as in a computer, it must be converted to an analog rasterscan before it can be displayed on the cathode ray tube.

Other spatial light modulators have been used in projection displays.For example, the use of a spatial light modulator drive for in a displaysystem is show in U.S. Pat. Nos. 4,638,309 and 4,680,579 issued to Ottand incorporated by reference hereinto. In Ott, a semiconductordeformable mirror device, in conjunction with a Schlieren opticaldevice, is used to form the spatial light modulator. Deformable mirrordevices are shown in U.S. Pat. Nos. 4,441,791, 4,710,732, 4,596,992,4,615,595, and 4,662,746, and U.S. patent application Ser. No. 168,724,filed Mar. 16, 1988 by Hornbeck, all of which are incorporated byreference hereinto.

Another display utilizing a light valve is shown in U.S. Pat. No.3,576,394 by Lee, which is incorporated by reference hereinto. Varioustypes of human factors information on critical flicker frequency isshown in "Applied Optics and Optical Engineering" (1965), Volume II (TheDetection of Light and Infrared Radiation), by Rudolf Kingslake, whichis incorporated by reference hereinto. Acousto-optic spectral filtersare shown in I.E.E.E. Transactions on Sonics and Utrasonics, vol. su-23,No. 1, January 1976, pages 2-22, which is incorporated by referencehereinto.

A HDTV (High Density Television) system is shown in U.S. Pat. No.4,168,509 by Hartman, which is incorporated by reference hereinto.Various types of electronic TV tuners are shown in U.S. Pat. Nos.3,918,002, 3,968,440, 4,031,474, 4,093,921, and 4,093,922, which areincorporated by reference hereinto. Various multi- frequency sensitivematerials for displays are shown in SPIE vol. 120 (Three-DimensionalImaging, 1977), pages 62-67, "PRESENT AND POTENTIAL CAPABILITIES OFTHREE-DIMENSIONAL DISPLAYS USING SEQUENTIAL EXCITATION OF FLUORESCENCE"by Carl M. Verber; and IEEE Transactions on Electron Devices, Vol.ED.-18, No. 9 (September 1971), pages 724-732, "A True Three-DimensionalDisplay" by Jordan D. Lewis et al, which are incorporated by referencehereinto. A type of Display is shown in Information Display,November/December, 1965, pages 10-20, "Three Dimensional Display ItsCues and Techniques" by Petro Vlahos, which is incorporated by referencehereinto.

Laser (Light Amplification by Stimulated Emission of Radiation) basedprojection systems are well known in the art. These systems may also usefluorescing pigments with non-visible laser light. This is shown in SIDINT. SYMP. DIGEST, Paper 10.1, May 1983, "Projection Display of RadarImage using Gas Laser and Organic Fluorescent Pigment Screen" by H.Yamada, M. Ishida, M. Ito, Y. Hagino and K. Miyaji, which is hereinincorporated by reference. More details on various pigments may be foundin CHEMISTRY AND CHEMICAL INDUSTRY, Vol. 23, No. 3, 1970, "IncreasingApplication Field for Fluorescent Pigment" by R. Takano, which is hereinincorporated by reference.

Laser based displays operate by deflecting a beam of coherent lightgenerated by a laser so as to form an image. The deflectors includedevices such as spinning mirrors and acousto-modulated deflectors. Thereare a number of problems with these projectors that have prevented themfrom becoming commercially feasible.

The first of these problems is flicker, which also places an upper limiton the resolution (i.e. number of pixels displayable) obtainable. Onlyone point of light (pixel) can be displayed at any given moment due tothe nature of the deflectors. Also, there is no persistence to thedisplay as these projectors generally direct the light onto a diffusionsurface which have no means of continuing to emit light after the lightis deflected away. This means that all points to be displayed must beilluminated within a time period less than the critical flickerfrequency (CFF) of the human eye.

A second problem is laser speckle. This is considered to be a randominterference pattern of intensity which results from the reflection ortransmission of highly coherent light from (or through) an opticallyrough surface (one whose local irregularities in depth are greater thanone quarter of a wavelength). This phenomenon is dealt with in JOURNALOF THE OPTICAL SOCIETY OF AMERICA, Vol. 66(11), 1976, page 1316,"Topical issue on laser speckle" by N. George and D. C. Sinclair;APPLICATIONS OF OPTICAL COHERENCE (W. H. Carter, Ed.), 1979, pages86-94. "Role of coherence concepts in the study of speckle" by J. W.Goodman; and COHERENT OPTICAL ENGINEERING (F. T. Arecchi and V.Degiorgio, Eds.), 1977, pages 129-149, "Speckle interferometry" by A. E.Ennos, all of which are incorporated herein by reference. Techniques forreduction of speckle are also shown in JOURNAL OF THE OPTICAL SOCIETY OFAMERICA: PART A, Vol. 5(10), 1988, pages 1767-1771, "Effect of luminanceon photoptic visual acuity in the presence of laser speckle" by J. M.Artigas and A. Felipe and OPTICS COMMUNICATIONS, Vol. 3(1), 1971,"Elimination of granulation in laser beam projections by means of movingdiffusers" by E, Schroder, all of which are incorporated herein byreference.

Another problem has been the generation of color images. This requiresthe use of multi-colored lasers. There are great technical difficultiesin both aligning multiple deflectors and in keeping them synchronized soas to simultaneously image the different colors at a given pixellocation.

As shown in the above articles and Patents there have been attempts toimplement three dimensional displays. None of these constructionsprovides a practical true three dimensional display. Further, as shownin the above articles there have been attempts to implement twodimensional displays using light valves, lasers, and deformable mirrordevices. None of these constructions provides a two dimensional displaywhich is adaptable to many different TV and computer display formats andprovides a fully digitized video display system using deformable mirrordevices.

SUMMARY OF THE INVENTION

The preferred embodiments shown herein show various concepts in thefield of digitized video and imaging systems with moving displaysurfaces and spatial light modulators. Several element on the surface ofa spatial light modulator may be used to form on pixel on a movingdisplay surface. The elements of a spatial light modulator can becontrolled using pulse width modulation techniques for varyingintensities.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described with reference to theaccompanying drawings, wherein:

FIGS. 1a, 1b, 1c, and 1d shows a two dimensional digital video systemutilizing a deformable mirror device;

FIGS. 2a, 2b, and 2c shows a two dimensional digital video systemutilizing a deformable mirror device and a laser;

FIG. 3 is a block diagram of the electronics for a digitized videosystem;

FIG. 4 shows a two dimensional digitized video system capable ofproducing a color image;

FIGS. 5a, 5b, and 5c show graphs and a color wheel;

FIG. 6 shows a two dimensional display;

FIG. 7 shows another view of the display of FIG. 6;

FIG. 8 is a top view of a spatial light modulator;

FIG. 9 is a circuit diagram of a memory cell of a deformable mirrorarray;

FIG. 10 is a flow for the electronics of FIG. 3;

FIG. 11 show a three dimensional digitized display system;

FIGS. 12 and 13 show a pointer for the system of FIG. 11;

FIG. 14 shows a pointer for the system of FIG. 11;

FIG. 15 shows a pointer for the system of FIG. 11;

FIG. 16 shows a multi-dimensional array processor; and

FIG. 17 shows a display with a moveable surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1a, 1b, 1c, and 1d show a preferred embodiment of a twodimensional digitized video system 75, which has an image generatingsystem 1 and display screen 2. The display screen 2 may be a relativelyflat sheet of an appropriate material, or it may be of curvedconfiguration so as to concentrate the reflected light toward a viewer.Optionally, the display screen 2 may be translucent so as to allow forback projection. In the reflective (or front projection) mode, thedisplay screen 2 may be composed of a rigid material such as plastic,metal, etc. and have a reflective surface. The surface may be a mattefinish or lenticular pattern as is well known in the art. In the backprojection mode, the display screen 2 may be composed of glass or atranslucent plastic and may have a patterned surface so as to partiallydiffuse the light impinging on it from image generating system 1.Back-projection screens of this type are well-known in the art.

A light source 10 is used to generate light energy for ultimateillumination of display screen 2. The light source 10 may be ofconventional structure such as incandescent, halogen, arc, or othersuitable form. Light 9 generated is further concentrated and directedtoward lens 12 by mirror 11. The mirror 11 may be of any suitable shapesuch as parabolic, ellipsoid, etc.

Lens 12, 13, and 14 form a beam columnator operative to columnate light9 into a column of light 8. This is done so as to concentrate the lightenergy and increase the efficiency of the overall system. Fold mirror 20is used to direct the columnated light 8 onto a spatial light modulator(SLM) 15 via path 7. Other structures may of course be used so as todirect a source of concentrated light energy onto SLM 15 withoutdeparting from the invention.

SLM 15 is operative to selectively redirect portions of light from path7 toward enlarger lens 5 and onto display screen 2 so as to from animage. In the preferred embodiment of the invention, the SLM 15 is of atype known as a deformable mirror device (DMD) which will be discussedin detail below. Other SLMs (such as Bragg cells, LCDs, etc.) could beused in either a reflective (as shown) or transmissive mode providedthat individual beams of light may be redirected at a high enough rate.The importance of the requirement of high switching speeds will becomeapparent below.

SLM 15 has a surface 16 upon which light from path 7 impinges. Thesurface 16 has a number of switchable elements (such as 17) that arecontrollable to redirect light toward the enlarger lens 5. For example,when element 17 is in one position, a portion of the light from path 7is redirected along path 6 to lens 5 where it is enlarged or spreadalong path 4 to impinge the display screen 2 so as to form anilluminated pixel 3. When element 17 is in another position, light isnot redirected toward display screen 2 and hence pixel 3 would be dark.

Computer 19 controls the operation of SLM 15 via bus 18 so as to formthe image on display screen 2 by selectively redirecting portions oflight on path 7 toward. The bus 18 provides the necessary controlsignals and image information from computer 19 to modulator 15. Thecomputer 19 can be, for example, a digital signal process (which isdiscussed in detail hereinafter).

In the preferred embodiment of the invention, surface 16 comprises anarray of deformable mirror cells. Deformable mirror cells suitable foruse in array 16 is shown in FIGS. 1b, 1c, and 1d. Four cells, 17, 27,37, and 47 are shown in FIG. 1b. The mirror 32 of cell 17 is connectedby hinge 30 to modulator 15 at about the location shown in FIG. 1b. Whenthe cell 17, is actuated, the mirror 32 is pulled downward from itsposition shown in FIG. 1c to its position shown in FIG. 1d. When thecell 17 is in the down position it directs light along optical path 6.When the mirror is in the up position of FIG. 1c, the portion of thebeam from optical path 7 is directed away from the optical path 6 anddisplay 2. The other portions of the array 16 which are not hinged, forexample, surface portion 34, also does not direct light toward display2.

In the presently preferred embodiment, it is seen that light is directedtoward the display screen 2 only when a mirror (such as 32) is in thedown position. This is because other portions of the array 16 (such assurface portion 34) may also be reflective and would add visual noise tothe display. In the preferred embodiment, light path 7 is substantiallyperpendicular to SLM 15 and light path 6 is at an angle. Otherembodiments are of course possible without departing from the scope ofthe invention. For example, light path 7 could be at an angle to SLM 15and light path 6 may be formed when a mirror element such as 32 is inthe up (or normal with surface portion 34) position. A Schlieren stopwould then be inserted prior to lens 5 so as to block unwanted lightsuch as from surface portion 34.

FIG. 2a shows another preferred embodiment of a two dimensionaldigitized display system of the present invention. This comprises animage generating system 50 and a display 51. The display has a pixel 52,which is one pixel of many pixels which make up the image for display ondisplay screen 51. The pixel 52 is located along optical path 53 from animage enlargement system 54 which can be of an suitable type such as alens system, fiber optic array, etc.

A laser 61 generates a beam of light 62. A beam expander 60, which canbe of any suitable type, serves to expand the small diameter beam oflight 62 from laser 61 into a larger diameter beam 63. This beam is thendeflected by fold mirror 55 onto SLM 56 along path 64. In this presentlypreferred embodiment, SLM 56 is of a different construction (as willbecome apparent below when discussing the FIGS. 2b and 2c) than thatshown in FIGS. 1a, 1b, and 1c. Mirror elements such as 58 of array 57are movable between two positions. In the "on" position, element 58redirects a portion of the light from path 64 along path 66 to enlarginglens 54 where it is enlarged (spread) along path 53 to impinge ondisplay screen 51 to form illuminated pixel 52. In the "off" position,the light is directed along path 65 where it will not impinge on thedisplay screen 51.

Display screen 51 may be of conventional structure as in the displayscreen 2 of FIG. 1a. However, as discussed in the BACKGROUND, laserspeckle is likely to result unless the screen 51 is optically smooth.For practical reasons such as difficulty in manufacture this isunlikely. Further, in order to increase the viewing angle, some sort ofdispersive surface (such as ground glass) should be used. This increasesthe amount of speckle unless the degree of dispersion will almosttotally dephase the coherent light impinging. Unfortunately, this hasthe side effect of blurring the image and thus decreasing apparentresolution.

The present invention overcomes the speckle problem in several ways.Images generated on display screen 51 are composed of a plurality oflight beams impinging on the surface simultaneously. A given light beamwill have a slightly different angle when it impinges the screenrelative to each of the others due to the effect of the enlarger lenssystem 54. Further, each light beam will have a slightly differentlength light path. This is additionally enhanced by the distance betweeneach of the mirror elements of array 57. Because of the differences inrelative angles and path lengths of the simultaneously impinging lightbeams, the relative phase of the beams is different when they impinge onthe display screen 51. This has the effect of reducing the overallcoherence of the light image and thus reducing the apparent specklewithout degrading the resolution.

Display screen 51 also has a transducer 90 coupled to it. The transducer90 sets up surface acoustic waves 91 that traverse the display screen 51with substantially parallel waves. An optional wave absorber 92 absorbswaves that have traversed display screen 51 so as to preventreflections. In other embodiments, transducer 90 may generate waves ofarcs or circles. Transducer 90 may be of conventional structure and ispreferably operative to generate signals in the ultra-sonic range so asto be out of the range of human hearing. Amplitude of the the surfaceacoustic waves 91 is greater than one wavelength of light. This servesnot only to dephase the relative beams of light, but also to disperse asingle beam. This is because the angle at which the beam impinges thedisplay surface 51 (and hence the angle at which the beam is reflectedor diffracted) varies due to the surface acoustic wave. The displayscreen 51 can be used in either a front projection or a back projectionmode.

In another embodiment of the invention, display screen 51 may comprise,or be coated with, materials known in the art (such as uranyl ions,lanthanum ions, erbium ions, organic daylight fluorescent pigments,etc.) that exhibit optical fluorescence when excited by non-visiblelight. Laser 61 generates either UV or IR (depending on the materialsselected) light. Preferably, display screen 51 is used in the backprojection mode. The side of display screen 51 facing the viewer(opposite from the side facing the image generator 50) is additionallycoated with a material that absorbs the light from the laser 61 so as tominimize any visual hazards. Optionally the coating may reflect thelight. For the reasons discussed below, the fluorescing material has adecay time that is substantially less than phosphors used inconventional CRTs.

SLM 56 is coupled to computer 59 by a control bus 70. Computer 59controls each mirror element (such as 58) of the array 57. These mirrorelements are switched between the "on" and the "off" positions to formthe image on display screen 51.

In an additional embodiment of the invention, computer 59 is alsocoupled to laser 61. Laser 61 is of the multi-mode or tunable type as iswell-known in the art. Computer 59 controls the output light frequencyof laser 61. By the techniques discussed below, a color display may begenerated by time sequencing the frequencies generated by laser 61.Similarly, display screen 51 may have a plurality of materials, eachfluorescing a different color depending on the frequency of theimpinging light beams.

A portion of array 57 is shown in FIG. 2b with deformable mirror cells48, 72, 73, and 74. Only cell 48 is discussed in detail. The mirror 110of cell 48 is movable about torsion hinges 112 and 113. The movement ofmirror 110 is best shown in FIG. 2c. Mirror 110 is movable about an axis116 from the position shown by dotted line 118 to the position shown bydotted line 134 relative to the normal surface 120.

In the "on" position, the edge 120 of mirror 116 touches landingelectrode 122. The mirror 110 is moved to the "on" position by applyingthe proper voltage to control electrode 124. The voltage on electrode isapplied to positive electrode 128 and through inverter 129 to negativeelectrode 130. A differential bias is applied to the mirror 130 throughan electrode 132. In the position shown by line 118, the mirror 130directs a portion of light beam from optical path 64 along optical path66 through system 54 along optical path 53 to pixel 52 on display 51. Ifa negative voltage (the "off" position) is applied to electrode 124,then the mirror 110 will rotate to the position represented by thedotted line 134 in FIG. 2c and directs a portion of light beam alongoptical path 65.

In FIG. 3, a signal source 140, which can be for example a TV tuner suchas those incorporated above, is connected through a bus 142 to anelectronics system 144. The bus 142 is connected to an analog to digital(A/D) converter 146. The analog signal received by A/D converter 146from bus 142 is converted by A/D converter 146 to digital codes on bus148. These digital codes are representative of the chrominance andluminance information of each pixel of an image. Bus 148 connects thedigital codes from converter 146 to a buffer memory 150. The digitalcodes from converter 146 are stored into buffer memory 150. In adifferent mode, digital codes or information can be loaded into buffermemory 150 through bus 152, for example, from a computer or graphicssystem. Indeed, in some embodiments of the invention, all informationmay come through bus 152 and signal source 140, bus 142, converter 146and 148 would not be needed.

Buffer memory 150 can be a single ported random access memory (RAM). Inthis case, bus arbitration between buses 148, 156 band 152 can behandled in a conventional manner by DMA (direct memory access)controllers as is well known in the art. First priority is given to bus148 (as there is no practical way of stopping data from coming in fromthe signal source 140). Second priority is given to bus 156 as it mustobtain display data very rapidly. Alternatively, the buffer memory 150can be of the dual or triple ported type for increased throughput.Design of multi-ported memory is also well-known in the art.

The digital codes or information, together represent an image that is tobe displayed. The digital codes within buffer memory 150 are transferredto a central processing unit (CPU) 154 through bus 156. The CPU can be astandard microprocessor such as a TMS 99000 (manufactured by TexasInstruments) or more desirably a digital signal processor (DSP), forexample, TMS 320C10, TMS 320C20, TMS 320C25, and TMS 320C30. Details ofthe use and structure of these DSPs are give in Digital SignalProcessing--Products and Applications "Primer" (1988), TMS 320C1x User'sGuide (1987), TMS 320C10 User's Guide (1983), TMS 320C2x User's Guide(1987), TMS 32020 User's Guide (1986), TMS 320C25 User's Guide"Preliminary" (1986), and TMS 320C30 User's Guide (1988), all of whichare incorporated by reference hereinto.

The CPU 154 is connected through bus 158 to a video memory 160, which ispreferably made up of video DRAMs (VRAMs) such as the TMS4461 from TexasInstruments, Inc. of Dallas, Tex. Preferably, a plurality of VRAMs isused, with the high-speed serial outputs of each VRAM corresponding to afew of the columns of the generated display on display screen 178. Thisis done so as to increase the load bandwidth of the planar projector172. The reason it is necessary to have a large load bandwidth willbecome apparent in the discussions below.

The CPU 154 decodes the video information, including chrominance andluminance, within the information from memory 150. The CPU 154 isprogrammed to extract image from that information and store that imageincluding chrominance and luminance into video memory 160. The image canalso be modified by CPU 154 under instructions through bus 162 or underthe control of its program. The buffer memory 150 and video memory 160comprises a memory 164 and could be constructed as a single memory.Further, the video memory 160 could be directly loaded from a graphicssystem or computer 166 through bus 168.

The electronic system 144 and the projection system 172 comprise animage generating system 174 which can use the image generating system 1in FIG. 1a with the spatial modulator 15 connected to video memory 160through bus 18. In the same manner, memory 160 can be connected tomodulator 56 in FIG. 2a through bus 70. In other words, the imagegenerating system shown in FIG. 3 has more detail for the electronicsand FIGS. 1a and 2a have more detail as for the optics and all of thevarious embodiments disclosed herein can be combined using the teachingsherein to construct various digitized display systems. The image storedwithin memory 160 is transferred through bus 170 to the projectionsystem 172 for display through an optical path 176 to display 178 suchin the systems shown in FIGS. 1a-1d and 2a-2c.

From the above descriptions, it can be seen that projector system 172 isa planar projector. In other words, all pixels that are to be displayedon display screen 178 are illuminated simultaneously rather than beingdisplayed sequentially by a raster. Further, data feeding projector 178comes from memory 160 while incoming data is buffered in buffer memory150. Thus the data rate to projector 172 is totally independent of theincoming rate from the signal source 140. This allows the presentinvention to be raster rate independent.

In the United States, the television broadcast standard is NTSC. Thisrequires an interlaced refresh rate of 60 hertz. In other countries,refresh rates may be 50 hertz. The raster rate is of course directlytied to the refresh rate. In particular, Europe uses PAL and CCAM as thestandards which have 50 hertz rates. As the present invention is rasterrate and refresh independent, it can be freely used in any country. TheCPU 154 merely has to detect the frequency of the sync signal (or usethe color burst or other known techniques) to determine how to store thedate to memory 160. In an alternate embodiment, a switch is provided toallow the user to select the standard used. In still another embodiment,signal source 140 would provide CPU 154 with a signal associated withthe broadcast frequency tuned to in order to inform CPU 154 of thebroadcast standard used.

In the presently preferred embodiment of the invention, the SLM used inthe projector system 172 comprises an array of 1280 by 800 cells. Thusthe display image on display screen 178 has a resolution 1280 by 800pixels (each pixel corresponding to one cell). Of course any size may bechosen depending on the application.

The NTSC broadcast standard has an image resolution of approximately 320by 200 pixels. A simple way of displaying NTSC data on the display ofthe present invention would be to control a sub-array of 16 cells (i.e.a 4 by 4 sub-array matrix) for each of the pixels. However this wouldtend to make a magnified projected image appear very coarse. In thepresently preferred embodiment, the NTSC data loaded into buffer memory150 is processed by CPU 154 before being loaded into memory 160. Thisprocessing uses the well-known nearest-neighbor algorithm to interpolateintermediate display pixels in both the horizontal and verticaldirections, since at least one entire frame of data (or at least severallines of data) may be stored in buffer memory 150. Thus for each pixelof NTSC data, 15 additional pixels are computed by CPU 154. Additionaland/or alternate processing, including other algorithms than thenearest-neighbor algorithm presently preferred, may be used. This servesto smooth the image and to increase apparent resolution

Likewise, if the incoming data has an image resolution greater than canbe displayed by projector 172 (i.e. greater than the number of cells ofthe SLM), CPU 162 applies processing routines to the data in buffermemory 150 before storing the results in memory 160. This processing isagain based on looking at a matrix subset (i.e. neighboring horizontaland vertical pixels) of the image data in buffer memory 150. A computedpixel is then output to memory 160 for display by projector 172 ontodisplay screen 178. Since every pixel to be displayed is computed, thereis no need for the incoming data resolution size to be any wholemultiple of the display resolution. Thus the present invention istotally standard independent, in both data rate and resolution.

FIG. 4 illustrate another embodiment of the invention. In FIG. 4, theimage generating system 210 has an electronics system 212 and projection214. This a color system with a green laser 216, red laser 218, and bluelaser 220. The green laser 216 produces a beam of green light alongoptical path 222. The red laser 218 produces a beam of red light alongoptical path 224. The blue laser 220 produces a beam of blue light alongoptical 226. A combining mirror 228 passes the green light from opticalpath 222 through to optical path 230 and redirects the red light fromoptical path 224 to optical path 230. Another combining mirror 232 islocated along optical path 230 to pass the green and red light fromoptical path 230 through to optical path 234 and redirect the blue lightfrom optical path 226 to optical path 234.

A beam expander 236 expands the light from optical path 234 into a beamof larger diameter along optical path 238. The light from optical path238 is reflected from mirror 240 onto a spatial light modulator 242,which can be a deformable mirror device, such as the device shown inFIGS. 2b and 2c. The mirror 240 redirects the light from path 238 tooptical path 250. The light from path 250 impinges onto spatial lightmodulator 242. If the control signals from memory within the electronicssystem 212 (only computer system 243 and bus 244 is shown), have applieda positive voltage to deformable cell 246 it will rotate to the left (asshown in FIG. 4) or to the right of a negative voltage is applied. Ifthe control signals from memory within the electronics system 212, (onlycomputer system 243 and bus 244 is shown) have applied a negativevoltage to deformable cell 248, it will to rotate to the right (as shownin FIG. 4) or will rotate to the left if a positive voltage is applied.This is also discussed in somewhat more detail in FIGS. 8 and 9herebelow.

As shown in FIG. 4, the portion of the light from optical path 250associated with cell 246 is redirected along optical path 252. Opticalpath 252 does not intersect projection system 254 or display (or screen)256. The portion of the light from path 250 associated with cell 248 isredirected along optical path 258. Optical path 258 intersectsprojection optics 254. The light beam redirected from cell 248 alongoptical path 248 is expanded and directed onto display 256 by projectionoptics 254 along with all of the other cells (not shown) on spatiallight modulator 242 which are rotated to direct light toward projectionoptics 254. This forms an image on display 256, which is located alongoptical path 260 from projection optics 254. The laser 216, 218, and 220are actuated in sequence by the electronics system 212. The computer 243loads the appropriate information for each color. For example, when thegreen laser 216 is to be actuated, the information of the green portionof the image is loaded into modulator 242. This is discussed in detailbelow. The projection optics 254 could, for example be a lens system ora fiber optics array.

The critical flicker frequency (CFF) of the human eye is of concern inthe present invention. The CFF is the frequency at which the eye is nolonger able to perceive a flickering (i.e. rapidly changing from dark tolight) image as distinct flashes, but rather as a continuous source oflight. This frequency changes as the intensity of the source changes.For example, at low luminosity (retinal illumination of -1.6 photons)the CFF is approximately 5 hertz. At higher levels of luminance (retinalillumination of 5 photons) the CFF is greater than 60 hertz. The eye hasan integration time of 100 to 200 milliseconds (depending on intensity)before it can accurately perceive the relative intensity of a lightsource. Because of this, luminosity can be varied for each pixeldisplayed by the system of the present invention by rapidly modulating aconstant source of light.

Similarly, the eye also has an integration time for color. This meansthat by sequencing a plurality of colors, the eye will merge them into asingle color. For example, if the color primaries red, green and blueare rapidly sequenced, the eye will see a white source. By varying theintensity of each primary (including by the time modulation discussedabove), any color can be selected.

The SLM of the present invention is capable of being modulated at a veryhigh rate. For example the mirror cells have a switching time betweenoff and on of about 10 microseconds. Likewise the array is able toaccept control data at a very high rate. How this is achieved is shownin FIGS. 8 and 9. In the presently preferred embodiment of theinvention, the entire mirror cell array of the SLM is able to be loadedand each cell switched during a time period of 20 microseconds.

As a consequence of this high switching ability, the SLM of the presentinvention can modulate each pixel at a data rate 833 times faster thanthe CFF for a bright image. At lower levels of desired luminance, thedifferential rate is of course much higher. The present invention isable to achieve wide dynamic range of both chrominance and luminance dueto this speed.

An example of how different luminance levels are achieved is shown inFIG. 5a. For simplicities sake, each time period (T1, T2, . . . T25) isassumed to be 4 milliseconds although as stated, the SLM of the presentinvention operates much faster. This is done merely to illustrate thatvarious luminance levels can be achieved even at these slow rates andstill be faster than the critical flicker frequency. Every largeincrement of time (corresponding to 4 time slices of 4 millisecondseach) represents the same pixel location on the screen and the intensitydesires as received from the signal source. The horizontal linesrepresent the signal provided to the SLM. For example when thehorizontal line is in the down position, the SLM does not direct lighttoward the display screen and when the horizontal line is in the higherposition, the light is directed toward the display screen.

The first large increment (encompassing time slices T2 through T5) showsthe SLM as not directing any light toward the screen. Thus the displayedlocation of the pixel would not be illuminated. During the second largeincrement (encompassing T6 through T9), the pixel is fully illuminatedand would be at its most visibly bright state. The next increment(represented by T10 and T13) illustrate half intensity. In other words,during half of the total time, light is not directed toward the screenand half the time it is.

The next two large increments (represented by T14 through T17 and T18through T21) have equal intensity. This means that perceived intensityof the light is brighter than in the previous increments, but less thanthe second. However, the eye may perceive the increment spanning T18through T21 as marginally brighter than that of T14 through T17. This isbecause the eye has an intensity integration time. Because there is anextended period (T15 through T20) in which the light is on, the eye willstart to integrate this as a high level of brightness and consequentlymay perceive the period T18 through T21 as brighter. Variations in thepattern can thus be used to further increase the apparent dynamic rangeof luminosity.

FIG. 5b illustrates how this dynamic range can be further stretched.During each of the larger time increments (T2 through T5, T6 through T9,etc.) the light source itself is modulated in intensity. While thepattern shown is of a sawtooth type, any pattern can be used such aslogarithmic, exponential, etc. Looking at FIGS. 5a and 5b together itcan be seen that the perceived brightness of increment T10 through T13would be greater than T22 through T25, even though both increments havetwo on and two off.

Modulation of the light source can be achieved in a variety of ways. Forexample, in the laser based projection system of FIG. 2a, the laser canbe controlled either by computer 59 or other circuitry to rapidly changeits intensity of generated light. For conventional light sourcegenerator systems as shown in FIG. 1a, a variably grated wheel such asthat shown in FIG. 5c could be spun in the light path prior to the SLM15. Preferably this spinning wheel would be placed between light source10 and lens 12 to help maintain the columnated beam.

Color can be added by sequencing different color primaries (for examplered, green and blue) during a time interval less than the CFF time. Theeye will temporally integrate distinct colors into a single color ifthey are sequenced fast enough. The system of FIG. 1a may have coloradded by spinning a wheel such as shown in FIG. 5c within the light pathleading to SLM 15. Used in this manner, the wheel of FIG. 5c has eachmajor section acting as a different color filter. For example onesection would filter all but red, the next all but blue, and the thirdall but green. Thus a single wheel would allow both luminosity controland color control. The wheel shown in FIG. 5c is by way of illustrationonly as the wheel could be divided into more color sections, or becomprised of wedges, or other configurations as may be appropriate.Other embodiments may use other filter systems such as acousto-opticspectral filters.

Color can be added to the system of FIG. 2a by using a multi-mode ortunable laser 61. Each color would be selected by tuning the laser 61 toa different frequency at a relatively rapid rate. The system shown inFIG. 4 of course has three color lasers (216, 218 and 220). These wouldbe sequenced. Alternatively, all pixels of a given color (derived fromvarious combinations of the three lasers 216, 218 and 220 generatinglight simultaneously by a different intensities) could be displayed atonce. The next set of pixels of a different color or intensity would bedisplayed, and so on. Of course, pixels of different luminosities but ofthe same color could be handled by the technique of modulating the SLMwithin time slices as discussed above.

Different sequence than those discussed above are possible. For example,blue light sources (such as laser 220 of FIG. 4) tend to be moreexpensive for the same light output than red or green. It would then bebetter to follow a pattern such as red, blue, green, blue, red, etc.

Another embodied of the invention that adds color is to opticallycombine three projectors such as those shown in FIGS. 1a and 2a so thata single image is obtained. Each of the projectors would be responsiblefor only one of the color primaries.

FIGS. 6 and 7 are another example of a useful projection optics 310. Alight source 312 produces a beam of substantially parallel light alongoptical path 314. Spatial light modulator 316 is located along opticalpath 314. As with the other spatial light modulators, some of the lightis directed along an optical path 318 toward display 320 to form animage and the remainder of the light is not. In FIG. 7 this remainder ofthe light is directed along optical path 322 and intercepted by plate324 and does not reach the display 320. A serrated lens 326, which canbe a single piece of molded plastic, is located along optical path 318.The light is reflected in parallel along optical path 328 as receivedbut the image is enlarged in the vertical direction as shown in FIG. 7.Note differences in width between the dotted line of optical path 318and 328. The light reflected along optical path 328 is directed onto aserrated lens 330. The light reflected from lens 330 and onto display320 is still parallel but is enlarged in the horizontal direction asshown in FIG. 7. The lens 330 is located behind display 320 and only aportion is shown in FIG. 7 and is shown better FIG. 6. In FIG. 6, theprojection system 310 of FIG. 7 has been replaced by planar projector332. Lens 326 enlarges the light from optical path 318 in the Xdirection and lens 330 enlarges the light from optical path 326 in the Ydirection. The light is reflected from lens 330 in the Z direction tothe display 320. The lenses 326 and 330 are serrated or stair stepped,which can be best seen in FIG. 6 from the side view of lens 326. Eachstep has a reflecting surface, for example, surface 340 and anon-reflecting surface 342, for example. The reflecting surface may bestraight (as shown) or optionaly may be curved. A curved reflectingsurface will spread or enlarge an impinging beam of light. If the curvedembodiment is employed, then it may be unnecessay to break a beam into aplurality of smaller beams as the desired enlargement will still occur.The lenses 326 and 330 are therefore, narrow at one end (the bottom asshown in FIG. 7) and thicker at the other end (the top as shown in FIG.7).

If highly columnated light is used in the display system of FIGS. 6 and7, the enlargement actually results in a plurality of spaced, smallerbeams of light impinging the display surface. In the preferredembodiment, the display surface is a highly dispersive surface (such asground glass) that will serve to blur the beams together so as to form alarger pixel. In an alternate embodiment, the display surface may becoated, as discussed above, with pigments that will fluoresce whenexcited by the impinging light.

As shown in FIG. 8, a spatial light modulator 410, which is a deformablemirror device 412, is constructed on a single substrate. The details ofconstruction of deformable mirror devices is set forth in the Patent andPatent Application incorporated above. The timing for the device 412 canbe located in one or more locations, for example, timing circuit 414. Asquare array 416 of deformable mirror cells is shown. The cells can bethose shown in FIGS. 2b and 2c, arranged in row and columns. The arrayas shown is 1280 by 840 cells, but it can be of any convenient shape,for example, rectangular or circular and be of any convenient size suchas 320 by 200 cells. A register 418 is located between the timingcircuit 414 and the array 416 along the top (as shown in FIG. 8) ofarray 416. The register 418 can be a shift register and can be made upof several different registers. The register has a number of taps 420,for example, 10 or 100 as necessary to insure that the register can beloaded at the required speed. The taps are connected to a bus (such asthe bus 170 in FIG. 3). The timing circuit can provide most of therequired address signals for loading the information into array 416 orthat can be provided through the bus.

A decoder 422 is located along another side of the array (the left sideas shown in FIG. 8). The decoder 422 provides the necessary controlsignals to select the appropriate row within array 416, in response toan address for the information in register 418 to be loaded. The decoder424 is located along another edge of array 416 at the bottom as shown inFIG. 8. The decoder 424 provides the necessary control signals to selectone of several memory cells associated with all or at least most of thedeformable mirror cells in array 416. A counter or commutator withineither timing circuit 414 or decoder 424 provides the address of theproper memory cell to select. For example, a pixel code laded intomemory cell 1 of 3 associated with each deformable mirror cell can bedisplayed by selected memory cell 1 of all or at least most of thedeformable mirror cells, for example, memory cell 426 of FIG. 9. Itshould be noted that decoder 422 must not only determine which row ofdeformable mirror cells to select, but also which of the memory cellassociated with those deformable memory cells to select.

As shown in FIG. 9, the row selection lines 428, 430, 431, and 432, fromdecoder 422 are connected to the gates of NMOS access transistors 436,437, and 438, respectively. The data lines 440, 446, 447, and 448, fromregister 418 are connected to one side of the source to drain paths oftransistors 436, 437, and 438, respectively. The other side of thesource to drain paths of transistors 436, 437, and 438 are connected tothe inputs of CMOS inverters 454, 455, and 456, respectively. Theinverters and access transistors could be replaced by standard DRAMcells, or SRAM cells. Only inverter 454 will be discussed in detail.Inverter 454 has a PMOS transistor 460 and an NMOS transistor 462. Thegates of transistors 460 and 462 are connected to the input of inverter454. One end of the source to drain paths of transistors 460 and 462 isconnected to the output of inverter 454. The other end of the source todrain path of transistor 460 is connected to the supply voltage (Vcc)and the other end of the source to drain path of transistor 462 isconnected to ground.

The outputs of inverters 454, 455, and 456 are connected to one end ofthe source to drain paths of transistors 468, 469, and 470,respectively. The other side of the source to drain paths of transistors468, 469, and 470 are connected to node 472. Node 472 is connected tothe input of inverter 474. The inverter 474 has a PMOS transistor 478and an NMOS transistor 480. The gates of transistors 478 and 480 areconnected to the input of inverter 474 and node 472. One side of thesource to drain path of transistors 478 and 480 are connected to theoutput of inverter 474, which is the input to the deformable mirror cellsuch as the control electrode 124 (FIG. 3). The gates of transistors468, 469, and 470 are connected to memory cell selection lines 484, 485,and 486, respectively, which are 3 of the selection lines 488 fromdecoder 424. Decoder 424 could be viewed as providing the read functionof the memory cells and decoder 422 as providing the write function. Itis useful to have at leas 2 memory cells per deformable memory cell, andwhile 3 memory cells are shown in FIG. 9, any number can be used asnecessary.

In operation, selection line 436 is brought high and transistor 436turns on allow a high (`1`) or low level (`0`) to be stored on the inputof the inverter 454 as applied from line 446. The selection line 436goes low and transistor 436 turns off storing the applied voltage on thegates of transistors 460 and 462. If the signal is high, then transistor462 is on, applying ground to the output of inverter 454 and turningtransistor 460 off. If the signal is low, then transistor 460 is on,applying the supply voltage to the output of inverter 454 and turningtransistor 462 off. Thereafter, when it is desired to display the pixelof information stored in inverter 454, the selection line 484 is broughthigh and the inverts of the `0` or `1` stored. Inverter 474 will invertits input and the `1` or `0` is applied to the deformable mirror cellform the output of inverter 474.

While the information on inverter 454 is being displayed, one or both ofthe inverters 455 and 456 can be loaded with information. Further,inverter 454 can be loaded while the information on either inverters 455and 456 is being displayed. It should be noted that lines 446, 447, and448 can be made as one line connected to transistors 436, 437, and 438.It should be noted that the circuits of FIG. 9 could be implemented inNMOS, PMOS, CMOS, GaAs, Bipolar, CCD or any other convenient technology.Thus, one preferred embodiment of a display cell 490 is shown in FIG. 9with its inverters, access transistors, and selection transistors.

FIG. 10 shows a flow diagram for the operation of the CPU 154 of FIG. 3.The logic flow begins at step 510 and proceeds through line 512 to enterlogic step 514. In step 514, the information in memory 150 is examinedto determine which broadcast standard is being received, for example,HDTV, NTSC, PAL etc. or which computer display information is beingreceived through bus 152, for example, from a color graphics adapter, anenhanced color graphics adapter, or a video graphic array. This can bedone by locating the synchronization pulses, vertical and horizontal, aswell the chromatic and intensity components of the information. Thelogic then proceeds through line 518 and enters logic state 520. Withinlogic state 520, a test is made to determine if the standard has beendetermined. If the standard has not been determined, then the logicproceeds through line 522 and reenters step 514. If the standard hasbeen determined, then the logic exits state 520 and proceeds throughline 524 to logic step 526. In step 526, the logic locates theinformation within memory 150 for an image and preferably the start ofan image.

Once the standard is known then the data can, for example, be examinedfor the vertical synchronization pulse. The logic then exits the step526 through line 528 and enters logic stat 530. If an image is present,then the logic exits state 530 through line 532 and enters step 534. Instep 534 the image is stored in the proper format into memory 160. Thelogic the proceeds from step 534 through line 538 and reenters step 526.If an image not present, then the logic exits state 530 and reentersstep 526 through line 540. Under certain conditions such as a change ofchannels the logic exits state 530 through line 543 and enters step 544.Step 544 could lead the logic to reenter step 510 or some otheroperation such as displaying the number of the new channel could beperformed.

Further, a switch could be provided to allow the user to set thestandard manually. Also, the standards for many channels could be storedin EPROM which is read by the CPU 154 using the channel informationsupplied by the signal source 140. Therefore, the switch or EPROM wouldbe examined in step 514 and the standard determined in state 520.

As shown in FIG. 11, a true three dimensional digitized video system 610is shown. System 610 has a display 612, which includes at least onemulti-frequency sensitive material, and tow spatial modulators 616 and617. One or more beams of energy are supplied along each of opticalpaths 620 and 621 to impinge on modulators 616 and 617, respectively.These beams are preferably substantially parallel and beam expanders(not shown) expand the beams to intersect the lens systems along opticalpaths 624 and 625 to intersect lens systems 628 and 629, respectively.Lens systems 628 and 629 redirect the beams into substantially parallelbeams into display 612. A hand held pointer 635 is shown for providingthe user with the ability to interact with the computer driving thedisplay, for example, enlarging a selected area, placing or moving anobject within the display 612, providing a selected point for rotatingthe image within the display about, or any of the tasks associated withcomputer aided design systems.

The modulators 616 and 617 can be any of the several described herein.However, modulator 617 can be of a different type since it is providingan output beam along a horizontal (as shown in FIG. 11) line, forexample, line 638. The modulator could also be a scanning horizontalbeam. The modulator 617 is controlled either internally or externally toprovide the lines in a known sequence synchronized with the informationloaded onto modulator 616. The known sequence could be all odds and thenall evens or all evens and then all odds, or from the top to the bottomor from the bottom to the top. Thus, the line of energy provided bymodulator 617 defines a plane within the display 612, for example, plane640. The voxels to be displayed are those for which an associated cellon modulator 616 directs an individual portion of the impinging energybeam along optical path 624. Thus, one plan of the image 650 isdisplayed at a time.

If the display 612 is monochrome then perhaps only two beams of energyof different frequencies need be provided along optical paths 620 and621. If color is to be provided then several beams of differentfrequencies should be provided in a sequence. For example, beams alongoptical paths 620 and 621 could cause a multi-frequency sensitivematerial within display 612 to luminesce red in the plane where bothbeams are present. Then beams with one or more different frequenciescould cause a multi-frequency sensitive material to luminesce blue andother beams could cause a multi-frequency sensitive material toluminesce green. Then, the next plane in the sequence would be providedwith red, green, and blue information. Of course, all of the planes ofdisplay 612 could be provided with red followed by green and blueinformation, if desired. If intensity information is provided then theremay be several different intervals for displaying red-green-blueinformation for each of the planes, as necessary. Additional memorycells could be provided on in addition to cell 426 to store theadditional intensity information. Thus, the image 650 is generated aplane at a time in order to display a full 3 dimensional image. Thesystem 610 of FIG. 16 can be modified to provide all of the colorinformation simultaneously. Three spatial modulators could be providedwith the red, green, and blue, respectively, information. An appropriateoptical system would be provided to direct all three beams along opticalpath 624. The appropriate additional energy beams would also have to beprovided along optical path 625. Thus an entire plane with all colorinformation could be displayed simultaneously.

Although two dimensional television signals could be displayed indisplay 612, the digitized video system of FIG. 11 could be furthermodified in at least two ways to provide a two dimensional display.First the display could be thinned in the horizontal direction to form athin sheet against lens system 629. Modulator 616 would be similarlythinned with one or more rows of cells remaining. If several rows areprovided, some or all of the rows could provide redundancy if some ofthe cells in one row fail. Also, if several rows are used the intensitycould be varied according to the number of cells in that column whichare displayed. For example, if four bits of intensity information wereprovided then if the maximum intensity was desired the four cells onthat column could all be on and all four voxel would be displayed at theproper time. Modulator 617 would operate as discussed above. Second, thedisplay could be thinned in the vertical direction to form only a thinarea next to lens 628. The modulator 617 could be replaced by an energysource providing a plane of energy through the display. The entire twodimensional image is displayed simultaneously.

The beam expanders and lens systems of FIG. 11 could be replaced by theserrated mirrors of FIGS. 6 and 7. Sensors 655-660 are provided todetect radiation from or generated by the pointer 655. More or fewersensors could be provided as necessary. In one embodiment, the pointerproduces an energy beam at one frequency which interacts with anotherenergy beam within the display. This interaction is detected by sensorsto determine the line of the pointer through the display 612. In anotherembodiment, the emissions of the pointer is detected by sensors 655-660directly to determine the line along which the pointer 635 is pointinginto display 612. The system 610 of FIG. 16 is useful for hostileenvironments such as airplanes and tanks. The display 610 could be solidor gas with a cubic enclosure. The display could be of any convenientshape, for example spherical. The display 610 can have a coating oneither its inner or outer surface between the user and the display whichis transparent to the visible light produced within the display, andabsorbs or reflects the energy beams directed to cause luminesces. Thecoating and the multi-frequency sensitive material can be utilized asthe display 320 shown in FIGS. 6 and 7.

A type of pointer suitable for use with the digitized video system 610of FIG. 11 is shown in FIGS. 12 and 13. Pointer 710 shown in FIGS. 12and 13 has several buttons 712-714, which can be utilized to provided anencoded input to display 612. The front of pointer 710 is triangular inshape with beam generators 718-720 which can be IR devices. The outputfrom generators 718-720 can be detected by sensors 655-660 to determinethe line along which the pointer is directed into display 612. Buttons712-715 can provide information which is then encoded to be broadcastedby generators 718-720, for example, by turning the generators indifferent sequences or at different frequencies or both when aparticular button is pressed. Buttons 712 and 713 could indicate thatthe distance of interest within the display is further or closer,respectively. Button 714 could indicate that a drag should be performedand button 715 could lock and unlock the cursor. Hand grips 725 could beprovided. The cursor provided with the display could be the entire lineof the pointer through the display with a point highlighted to indicatedistance. The cursor could be an visible XYZ axis with one axis alongthe line of the pointer or an visible XYZ axis which is oriented withthe display.

FIG. 14 shows another pointer 730 which is hinged about pivot 732. Grips734 can be provided. Buttons 736 similar to buttons 712-715 areprovided. The beam generators 739 and 740 are provided at the ends ofthe segments 743 and 744. Segments 743 and 744 are pivoted about pivot732 which can move the point at which beams 446 and 447 coincide. Thusbeams 466 and 467 could be of different frequencies which cause amulti-frequency sensitive material to luminesce which is detected bysensors 656-660.

Another pointer 750 is shown in FIG. 15. This pointer 750 has a trigger752 and an elongated body 753. Buttons 754 and 755 are provided similarto buttons 714 and 715, respectively. Grips 758 can be provided. Trigger752 alters the angle of beams 760 and 761, which alters the distance atwhich the beams coincide. For example the closer the trigger movedtoward body 753 the beam intersect is moved closer to the body. Thebeams are generated by beam generators; only beam generator 763 is shownin FIG. 15. The beam generators can be similar to beam generators 739and 740 of FIG. 15.

The FIG. 16 illustrates a multi-dimensional array processor (MAP) 808coupled to a host processor 800 and a 3 dimensional display 801. Thehost 800 may include any type of computer system such as a personalcomputer, minicomputer, or even just a receiver system for broadcastinformation. The 3D display 801 may be of the type described above, thatdescribed below in connection with FIG. 17, or other suitable displaytypes.

In the presently preferred embodiment of the invention, the display 801displays the 3D image as N number of XY planes, thus forming an XYZimage. Other embodiments are of course possible without departing fromthe scope of the present invention. For example, the display maycomprise a number of XYZ blocks with one (or more) MAPs per block.Alternatively, each processing cell (for example 810, 820, and 830) ofthe MAP may operate on an XYZ basis rather than the presently preferredplane basis.

The MAP 808 is generally composed of a plurality of processing cells(PCs) 810, 820, and 830. As stated, in the presently preferredembodiment, each processing cell operates on an XY plane of the N planeimage. Only 3 processing cells 810, 820, and 830 are shown forillustration. PC 810 is for the first plane, PC 820 is for the secondplane, and PC 830 is for the Nth plane of the image. In otherembodiments, each PC may be responsible for several image planes.

Each processing cell 810, 820, and 830 includes a processor (811, 821,and 831 respectively) coupled via a bus (813, 823, and 833 respectively)to a plane memory (812, 822, and 832 respectively). The processors 811,821, and 831 may be of several different types. For examples: digitalsignal processors (DSPs) such as the TMS 320C30; conventionalmicroprocessors such as the TMS99000; or graphics signal processors(GSPs) such as the TMS34020 among others could be used. In the presentlypreferred embodiment, GSPs are used as they not only are programmable,but they are also designed to easily manipulate two dimensional (XY)data. Likewise, the memory used may be of different types. Video RAMs(such as the TMS4461), DRAMs, SRAMs, or other memories could be used.Preferably, the memory architecture is that of a two ported type. In thepresent embodiment, VRAMs are used as they are inherently dual portedwith the normal memory interface used for processor buses 813, 823, and833 and the high speed serial ports used for connecting to the displaybus 803.

The host 800 communicates with each processor 811, 821 and 831 withinthe MAP simultaneously over the high level descriptor language (HDL) bus809 and the control bus 804. Control bus 804 is used to signal when thehose 800 may send another HDL command (as described below) and tosynchronize the PCs with the display 801. Optionally, each processor maycommunicate with its neighbors via other buses. For example: processor811 and processor 821 communicate over bus 805; processor 821communicates with the processor for plane 3 (not show) via bus 806; andthe N-1 processor (not shown) communicates with processor 831 via bus807. As will be seen, the interprocessor communication is useful in some3 dimensional image manipulations.

An alternative embodiment (not shown) would have host 800 onlycommunicating with processor 811. All instructions to other processors(such as 821 and 831) would be allowed to "ripple" through theinterprocessor buses (805, 806, and 807).

Display bus 803 is used to provide display data to the 3D display 801.In the presently preferred embodiment, each PC (810, 820, and 830) issequentially allowed to place an entire plane of display data on bus 803before the next plane. For example: PC 810 places the first plane ofimage data on bus 803; next, PC 820 places the second plane of imagedata on bus 803; each PC following (now shown) also places its data onbus 803; finally, PC 830 places its plane on bus 803. The process thenrestarts. Of course, other sequences may be employed. In otherembodiments, each PC may be responsible for a block of XYZ informationand may place the entire block on bus 803, or interleave planes asdisplay 801 may require. In any event, all of the image data is presenton bus 803 at some point. Further, as display 801 must be frequentlyrefreshed (preferably faster than the critical flicker frequency), allof the image data is available in a relatively short period of time.

As will be seen below, each PC must have available to it the informationthat is present in other planes. While this could be done via theinterprocessor buses 805, 806, and 807, this would be relatively slow,particularly when the information must be provided from several planesaway. Therefore each processor (811, 821, 831) also is couples todisplay bus 803 via buses 816, 826, and 836 respectively. In thepresently preferred embodiment, buses 816, 826 and 836 are coupled intothe processor buses 813, 823, and 833 respectively. In anotherembodiment, each processor may have an additional port coupled todisplay bus 803. In still another embodiment, the plane memories 812,822, and 833 could be used to buffer data from display bus 803.

The high level descriptor language (HDL) used by host 800 to control thePCs of the MAP can be broken down into three basic types. These includestructure formation types (including arithmetic and logic operations ona predetermined set of points), fills, and moves (including rotates).All of these are performed in parallel as will be obvious from thedescriptions below.

Structure formation can include types such as line drawing, fractalgeneration, logic operations such as XORs, box drawing, etc. Forexample, if a line is to be drawn for display on display 801, thefollowing sequence occurs. Host 800 sends down a HDL command thatspecifies the type of instruction (i.e. line drawing) and a formulagiving the parameters of the line. Each PC of MAP 808 simultaneouslyreceives this command over HDL bus 809. All PCs, in parallel, evaluatethe formula to decide if the plane for which that PC is responsible foris affected. If so, then the PC will hold a common control line ofcontrol bus 804 down until it is finished. This prevents host 800 fromsending another command until all processing is finished. Each PC thatmust modify a point within its associated plane memory, will do so andthen release the control line. When all PCs have finished, the controlline will be allowed to rise and host 800 may issue another HDL command.

In the preferred embodiment, the control line is handled slightlydifferently. All PCs immediately hold the control line upon the receiptof a command and will release it when the PC is either finished ordetermines that the PC is not involved in the operation.

Fill instructions start in the same manner. Host 800 issues a fill HDLcommand to all PCs via bus 809. All PCs that immediately determine thatthey have to modify their respective planes will hold the control lineof control bus 804 down. However, in this case, because this is a 3dimensional fill, as a fill progresses in one plane, it may open "holes"or "leaks" in another plane that will force a PC that previously did nothave to modify its plane, to do so. There are two presently preferredways of informing previously uninvolved PCs that they have to modifytheir plane memories.

The first of these uses the interprocessor buses 805, 806, and 807. Whena given PC determines that it must modify its associated plane memory,it then informs the neighboring PCs via the associated interprocessorbus that it is doing so. The neighboring PCs then also hold the controlline down. When the given PC finishes, it informs the neighboring PCs ofthat fact and releases its hold on the control line. The neighboring PCshold the line down and then look to see if they will have to modifytheir plane memory. In order to determine this, they will either examinethe given PC's plane data as it passes on display bus 803, or they mayrequest data directly from the given PC via the interprocessor bus. Ifthe neighbors determine that they have no changes, then they willrelease the control line. If, on the other hand, changes are necessary,then they will inform their appropriate neighbors and the processdescribed repeats itself.

The second technique obviates the need (at least for this case) of theinterprocessor busses 805, 806, and 807. Each PC must not only be ableto pull the control line of control bus 804 down, but it also must beable to read the status of the control line. This functions as follows.If a given PC determines from the HDL instruction (or as will be seen,from passing data on bus 803) that it must modify its plane memory, itwill pull the control line down and modify its memory. When it isfinished, it must continue to hold the control line down for at leastone full cycle of all image data passing on bus 803. This allows thegiven PC to determine if it is really finished. In other words, ifanother plane has changed, then the given PC may also have to changeagain. If not, then the given PC will release the line. Any time theline is down after a HDL fill command, all PCs must constantly scantheir neighbor's plane data passing on bus 803 to determine if they needto start modifying. If so, then they will hold down the line and repeatthe above process.

The final class of HDL command is that of moves and rotates. Thecommands start in the same way. The Host 800 sends the command and allaffected PCs hold the control line. In the case of just and XY move orrotate (i.e. no interplane moves or rotates), all processors cansimultaneously perform the move in their associated plane and releasethe control line.

In the case of any move or rotate that involves the Z axis (i.e.requires interplane movement), all affected PCs hold the control linefor at least one full image cycle of data passing on display bus 803.This is done so that the associated processors may buffer all of theinterplane data that they will require. After the full image cycle, theaffected PC processors may modify their associated plane memory and thenstop holding the control line. No data is allowed to be modified until afull image cycle occurs so as to not contaminate data that another PCneeds.

As can be seen from the above discussion, the architecture for a true 3dimensional display processor is markedly different than that requiredfor a processor designed to represent a 3 dimensional image on a 2dimensional display. Computational power is not as critical, but dataflow is far more critical. As a consequence, the processors used in thePC may be simpler and smaller and hence more amenable to being put on asingle chip with the plane memory. Indeed, for many true 3D displays,the entire MAP may be implemented on a single substrate.

A type of three dimensional display is shown in Patent Application byGarcia and Williams, filed Aug. 8, 1988, U.S. Pat. No. 5,042,909, whichis incorporated by reference hereinto. In summary, the above referencedand incorporated patent details the use of such a moving surface tocreate an image thereon, which involves coordination of the movement ofthe surface with the generation of the light to be shown upon it. InFIG. 17, a surface with a 360 degree spiral surface 900 is rotated aboutan axis 902 to produce a three dimensional cylindrical space 904. Thesurface 900 extends from the axis 902 to the other edges of space 904 asshown in FIG. 17. As the surface 900 is rotated each point within space904 is intersected once during each rotation. The surface 900 could beof any convenient shape, for example, a circular disk. A light beam isprojected along optical path 906 to intersect with the surface 900. Theimage information can be provided by any of the systems shown hereinutilizing a spatial light modulator along optical path 906. In light ofthe above referenced patent and the coordination necessary to producethe image on the moving surface, it is inherent that the activation ofthe elements on such a spatial light modulator would have to becoordinated with the movement of the surface to be in the direction ofthe moving surface.

What is claimed is:
 1. A method for producing an image onto a movinglight-sensitive medium comprising the steps of:positioning a spatiallight modulator having a plurality of individually controlled switchableelements between the medium and the light source; and forming eachindividual pixel by activating said switchable elements such that eachindividual pixel is formed by a plurality of said switchable elementsand the intensity of each said pixel is controlled by the amount of timesaid switchable elements are in an ON state.
 2. Apparatus for exposingan image onto a moving light-sensitive medium comprisinga light source;a plurality of switchable elements disposed between said light sourceand said light-sensitive medium, and arranged in sub-arrays comprising apredetermined number of switchable elements; and activation circuitryconnected to said switchable elements operable to controllably activatesaid each said switchable element individually according to receivedimage data wherein pixels of said image are formed from a plurality ofswitchable elements, the intensity of said pixel being determined by theamount of time said elements are in an ON state.